/Engine/Source/Runtime/Engine/Public/Net/OnlineEngineInterface.h
the unique id for a given local user on the given OnlineSubsystem
virtual [FUniqueNetIdWrapper](API\Runtime\CoreOnline\Online\FUniqueNetIdWrapper) GetUniquePlayerIdWrapper ( [UWorld](API\Runtime\Engine\Engine\UWorld) * World, int32 LocalUserNum, [FName](API\Runtime\Core\UObject\FName) Type )